Measuring IgG levels is a cheap health insurance for the newborn foal

Veterinarian Susanna Häkkä and “Typy”, the first foal she helped to conceive. Photo: Emmy Heinonen.

Immunoglobulin G (IgG) antibodies are a crucial part of the foal’s immune defense system. The mare’s placenta does not pass antibodies, so the foal is born without any protective immunity. A good quality maternal colostrum is the source of the foal’s antibodies. Antibody deficiency exposes the foal to infections, in which case there is a risk of the foal becoming seriously ill or even dying.

Antibodies in the mare’s colostrum are absorbed through the foal’s digestive system. This is most effective during the first 6 hours after birth, whereas after about 12 hours absorption is almost non-existent. Antibodies can be measured by taking a blood sample from a foal aged (12-)18-36 hours.

Antibody measurement as an aid to treatment initiation

If the foal’s IgG level is over 800 mg/dL, the foal has received enough antibodies from colostrum. If the level is in the range 400-800 mg/dL, the foal has partial failure of immune transfer and the administration of plasma should be considered on a case-by-case basis. If the foal’s antibody level is below 400 mg/dL, the amount of antibodies is too low, and the foal must be given plasma intravenously. After plasma treatment, the rise in the foal’s IgG levels must be confirmed with a new blood sample after about a day.

There are several different reasons for low antibody levels, such as too little colostrum intake, low-quality colostrum, poor absorption of antibodies in the foal’s digestive system, and a sick or weak foal.

A numerical result supports the veterinarian’s work

I recommend testing of IgG levels for all foals. The level of the foal’s antibodies cannot be deduced from the foal’s external appearance!

I use a Labmaster LUCIA™ VET analyzer with which I get a quantitative result of IgG levels. The quantitative i.e. numerical result is particularly useful when the antibody levels are in the range of 400-800 mg/dL, in which case the exact result helps to make a decision about the necessity of plasma on a case-by-case basis.

Veterinarian Susanna Häkkä “VetSuski”